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Section 1.4
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1.4 Earth System Science
1 FOCUS
Section Objectives
1.9
1.10
1.11
1.12
Describe the primary goal of
Earth system science and
define the term system.
Describe Earth’s two major
sources of energy.
Explain how humans affect
Earth’s systems.
Distinguish between
renewable and nonrenewable
resources.
Key Concepts
How is Earth a system?
Vocabulary
◆
system
What is a system?
Where does the energy
come from that powers
Earth’s systems?
How do humans affect
Earth’s systems?
Reading Strategy
Outlining As you read, make an outline of
the most important ideas in this section. Begin
with the section title, then list the green
headings as the next step of the outline.
Outline further as needed.
I. Earth System Science
A. What is a System?
What makes a resource
renewable or
nonrenewable?
?
1.
?
2.
B.
?
Reading Focus
Build Vocabulary
A
L2
s we study Earth, we see that it is a dynamic planet with many
separate but interactive parts or spheres. Earth scientists are studying
how these spheres are interconnected.
This way of looking at
Earth is called Earth system science. Its aim is to understand Earth
as a system made up of numerous interacting parts, or subsystems.
Instead of studying only one branch of science, such as geology, chemistry, or biology, Earth system science tries to put together what we
know from our study of all of these branches. Using this type of
approach, we hope to eventually understand and solve many of our
global environmental problems.
Word Forms Have students predict
the meanings of open system and closed
system based on their prior knowledge
of the words open, closed, and system.
Have students verify their predictions by
reading the section.
Reading Strategy
L2
Earth System Science
A. What is a System?
1. System—any size group of
interacting parts forming a whole
2. Types of Systems—closed and
open
B. Earth as a System
1. Earth has two energy sources—the
sun and Earth’s interior.
2. The parts of the Earth system are
linked so a change in one part can
cause changes in all the other parts.
What Is Earth system science?
What Is a System?
Most of us hear and use the term system frequently. You might use
your city’s transportation system to get to school. A news report might
inform us of an approaching weather system. We know that Earth is
just a small part of the much larger solar system.
A system can be any size group of interacting parts that form
a complex whole. Most natural systems are driven by sources of energy
that move matter and/or energy from one place to another. A simple
analogy is a car’s cooling system. It contains a liquid (usually water and
antifreeze) that is driven from the engine to the radiator and back
2 INSTRUCT
What Is a System?
Build Science Skills
L2
Using Analogies The text gives an
analogy of a car’s cooling system to a
natural system. Challenge students to
think of other analogies between
human-made and natural systems.
They should write a description of
the analogy they choose, including
diagrams if appropriate. The
descriptions should explain how the
analogies are similar to the actual
process and different from it.
Verbal, Logical
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Chapter 1
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Build Reading Literacy
again. The role of this system is to transfer the heat generated by combustion in the engine to the radiator, where moving air removes the
heat from the system.
This kind of system is called a closed system. Here energy moves
freely in and out of the system, but no matter enters or leaves the system.
In the case of the car’s cooling system, the matter is the liquid. By contrast, most natural systems are open systems. Here both energy and
matter flow into and out of the system. In a river system, for example, the
amount of water flowing in the channel can vary a great deal. At one
time or place, the river may be fuller than it is at another time or place.
Refer to p. 216D in Chapter 8, which
provides guidelines for comparing and
contrasting.
Compare and Contrast Help
students understand the difference
between an open system and a closed
system. Have students make a
comparison chart, starting with the
definition of each type of system.
Have students classify each system
listed during the brainstorming session
as either an open system or a closed
system. Example:
Earth as a System
The Earth system is powered by energy from two sources.
One
source is the sun, which drives external processes that occur in the
atmosphere, hydrosphere, and at Earth’s surface. Weather and climate, ocean circulation, and erosional processes are driven by energy
from the sun.
Earth’s interior is the
second source of energy. There is heat that
remains from the time Earth formed. There
is also heat continuously generated by the
decay of radioactive elements. These sources
power the internal processes that produce
volcanoes, earthquakes, and mountains.
The parts of the Earth system are linked
so that a change in one part can produce
changes in any or all of the other parts. For
example, when a volcano erupts, lava may
flow out at the surface and block a nearby
valley. This new obstruction influences the
region’s drainage system by creating a lake or
causing streams to change course. Volcanic
ash and gases that can be discharged during
an eruption might be blown high into the
atmosphere and influence the amount of
solar energy that can reach Earth’s surface. The result could be a drop
in air temperatures over the entire hemisphere.
How do we know that Earth’s systems are
connected?
L1
Open
System
Closed
System
Definition
Energy and
matter move
in and out of
the system.
Energy
moves in
and out of
the system,
but matter
cannot enter
or leave.
Examples
weather system
river system
cooling
system
Have students research a list of systems.
Then have students put each system in
the correct column on their comparison
chart.
Verbal, Logical
Earth as a System
Build Science Skills
Figure 18 When Mount St.
Helens erupted in May 1980, the
area shown here was buried by a
volcanic mudflow. Now, plants are
reestablished and new soil is
forming.
Over time, soil will develop on the lava or ash-covered surface and,
as shown in Figure 18, plants and animals will reestablish themselves.
This soil will reflect the interactions among many parts of the Earth
system—the original volcanic material, the type and rate of weathering, and the impact of biological activity. Of course, there would also
Introduction to Earth Science
19
L2
Relating Cause and Effect Using this
section of the textbook, have students
make a concept map showing how a
volcanic eruption (an event of the
geosphere) can causes changes in
all the other spheres (hydrosphere,
atmosphere, and biosphere). Have
students use the concept map to make a
poster to be displayed in the classroom.
Challenge students to create a product
that is both visually appealing and
scientifically accurate. Ask students to
think of another event on Earth and
predict how it would affect all the other
spheres. Have students make another
concept map poster on this event.
Visual, Group
Customize for English Language Learners
Review with English language learners the
meanings of the words open and closed.
Help students relate the meanings of open
and closed to open system and closed system.
Before teaching the terms renewable resources
and nonrenewable resources, explain what it
means to renew a library book (take it out
again before you return it). Help students
relate this use of the word renew to the terms
renewable resources and nonrenewable
resources. Tell students that if they are not
allowed to renew a library book (nonrenewable)
it is often because the library does not have
enough books on that topic to meet the needs
of their patrons. Explain that a renewable
resource can be used as often as we like
because there is always more of it being made.
Answer to . . .
Earth system science is a
way of looking at Earth
as a system made up of several
interacting subsystems.
Events taking place in
one part can produce
changes in all the other parts.
Introduction to Earth Science 19
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Section 1.4 (continued)
be significant changes in the biosphere. Some organisms and their
habitats would be eliminated by the lava and ash, while new settings for
life, such as the lake, would be created. The potential climate change
could also have an effect on some life-forms.
The Earth system is characterized by processes that occur over areas
that range in size from millimeters to thousands of kilometers. Time
scales for Earth’s processes range from milliseconds to billions of years.
Despite this great range in distance and time, many processes are connected. A change in one component can influence the entire system.
Humans are also part of the Earth system.
Our actions produce changes in all of the other parts of the Earth system. When we
burn gasoline and coal, build breakwaters along a shoreline, dispose
of our wastes, and clear the land, we cause other parts of the Earth
system to respond, often in unforeseen ways. Throughout this book,
you will learn about many of Earth’s subsystems, such as the hydrologic
(water) system, the tectonic (mountain-building) system, and the climate system. Remember that these components and we humans are
all part of the complex interacting whole we call the Earth system.
L2
Students may think that only human
actions can seriously affect the environment. Use the example of the eruption
of Mount St. Helens to emphasize that
natural events can have widespread and
negative effects on the environment.
The 1980 eruptions spread ash over
much of eastern Washington. About
500 square kilometers of forest were
destroyed or damaged. Most large
animals in the area were killed by the
blast, but some small animals survived.
More than 20 years later, the area is still
fairly barren. It may take at least 200
years for the forest to be restored to its
previous state. Large mammals such as
elk have already repopulated the area,
along with birds, insects, and small
mammals.
People and the Environment
Environment refers to everything that surrounds and influences an
organism. Some of these things are biological and social. Others are
nonliving such as water, air, soil and rock as well as conditions such as
temperature, humidity, and sunlight. These nonliving factors make up
our physical environment. Because studying the Earth sciences leads to
an understanding of the physical environment, most of Earth science
can be characterized as environmental science.
People and the
Environment
Use Visuals
L1
Figure 19 This flood was caused by the
action of humans. Ask: What was the
actual cause of this flood? (building the
Aswan Dam) What are some ways
humans can cause floods or make
them worse? (by clearing forests,
building cities, and constructing dams)
Visual, Logical
What are examples of nonliving factors?
Figure 19 The benefit that was
intended by the construction of
the Aswan Dam in Egypt was not
achieved.
Drawing Conclusions How
might the flooding here have
been avoided?
Today the term environmental science is usually used for things that
focus on the relationships between people and the natural
environment. For example, we can dramatically influence natural
processes. A river flooding is natural, but the size and frequency of
flooding can be changed by human activities such as clearing forests,
building cities, and constructing dams. Unfortunately, natural systems
do not always adjust to artificial changes in ways we can anticipate. An
alteration to the environment that was intended to benefit society may
have the opposite effect, as shown in Figure 19.
Resources Resources are an important focus of the Earth sciences.
They include water and soil, metallic and nonmetallic minerals, and
energy. Together they form the foundation of modern civilization. The
Earth sciences deal not only with the formation and occurrence of
20 Chapter 1
Facts and Figures
One of the reasons it is often difficult to
predict how natural systems will respond to
unexpected changes is the prevalence of
positive and negative feedback mechanisms.
Processes that feed into changes, making
them more severe, are considered positive
feedback. As humans put more carbon dioxide
into the air, Earth may hold more of the sun’s
heat and begin to warm. This warming may
cause snow and ice near the poles to melt.
This melting may make Earth absorb more
20
Chapter 1
of the sun’s rays, thus increasing Earth’s
temperature further. This is an example of
positive feedback. Negative feedback
mechanisms work to return the system to the
way it was before the change. For example,
an increase in Earth’s temperature may result
in an increase in evaporation, and then an
increase in clouds. Clouds cause Earth to
reflect more of the sun’s rays back into space,
cooling Earth back down.
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these vital resources but also with maintaining supplies and the environmental impact of their mining and use.
Resources are commonly divided into two broad categories—renewable resources and nonrenewable resources.
Renewable resources
can be replenished over relatively short time spans. Common examples are plants and animals for food, natural fibers for clothing, and
forest products for lumber and paper. Energy from flowing water, wind,
and the sun are also considered renewable resources.
Important metals such as iron, aluminum, and copper plus our most
important fuels of oil, natural gas, and coal are classified as nonrenewable resources.
Although these and other resources continue to
form, the processes that create them are so slow that it takes millions
of years for significant deposits to accumulate. Earth contains limited
quantities of these materials. Although some nonrenewable resources,
such as aluminum, can be used over and over again, others, such as oil,
cannot. When the present supplies are exhausted, there will be no more.
Build Science Skills
L2
Problem Solving Explain that when
supplies of a nonrenewable resource
start running low, it is often possible to
substitute some other resource. Have
students work in small groups to
brainstorm and research alternatives to
oil that can be used when all of our oil
has been used up. If students are having
trouble getting started, suggest that
they focus on transportation and power
generation. Areas students can
investigate include natural gas, coal,
biodiesel, nuclear power, wind power,
and solar power. Have each group
present their results to the class.
Interpersonal, Logical
For: Links on environmental
decision-making
Visit: www.SciLinks.org
Web Code: cjn-1014
How do renewable and nonrenewable resources
differ?
L2
Population Figure 20 shows that the population of Earth
8
7
6.1 billion
(2000)
6
5
4 billion
(1975)
4
3
2 billion
(1930)
2
1 billion
(early 1800’s)
1
4000
Environmental Problems
2000
0
B.C. A.D.
Year
2000
0
World population (billions)
is growing rapidly. Although it took until the beginning of the
nineteenth century for the population to reach 1 billion, just
130 years were needed for the population to double to 2 billion.
Between 1930 and 1975, the figure doubled again to 4 billion,
and by about 2010, as many as 7 billion people may inhabit
Earth. Clearly, as population grows, so does the demand for
resources. However, the rate of mineral and energy resource
usage has increased more rapidly than the overall growth of the
population.
How long will the remaining supplies of basic resources
last? How long can we sustain the rising standard of living in
today’s industrialized countries and still provide for the growing needs of developing regions? How much environmental
deterioration are we willing to accept to obtain basic
resources? Can alternatives be found? If we are to cope with
the increasing demand on resources and a growing world
population, it is important that we have some understanding
of our present and potential resources.
Students may think that the world
population is expected to continue to
increase indefinitely. Tell students that
many demographers (scientists who
study changes in human populations)
expect population growth to slow down
over the next 100 years. In fact, some
predict that the total population may
even decrease. The reason for this is that
in many developed countries, people are
not having enough children to replace
themselves. Most current population
growth is occurring in developing
countries. However, as those countries
develop, their birth rates are also
expected to fall.
Figure 20 Growth of World
Population
In addition to the search for mineral and energy resources, the Earth sciences must also deal with environmental problems. Some of these
problems are local, some are regional, and still others are global. Humans
can cause problems, such as the one shown in Figure 21.
Significant
Introduction to Earth Science
21
Download a worksheet on
environmental decision-making for
students to complete, and find
additional teacher support from
NSTA SciLinks.
Answer to . . .
Figure 19 The flooding could have
been avoided by not building the dam.
Nonliving factors include
water, air, soil, rock,
temperature, humidity, and sunlight.
Renewable resources
can be replenished
over a relatively short time span.
Nonrenewable resources take millions
of years to accumulate.
Introduction to Earth Science 21
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Section 1.4 (continued)
Environmental
Problems
Build Science Skills
L2
Inferring Discuss with
students that events
such as earthquakes,
landslides, floods,
hurricanes, beach erosion from coastal
storms, and drought are natural
processes. Help students understand
that these natural processes become
hazards “only when people try to live
where these processes occur.” Provide
small groups of students with one or
more pictures of damage from natural
disasters. Some examples to use would
be flooded homes, a coastal home
about to be carried out to sea, buildings
damaged by an earthquake, or urban
flooding due to too much paved land.
Ask: What happened here? How could
this disaster have been prevented?
(Sample answer: This home is being
carried out to sea because it was built too
close to the ocean. These homes were
flooded because they were built on a flood
plain. This building was destroyed because
it was built too close to a fault line.) Have
students infer the answers to these two
questions, and then share their ideas
with the class. Use this as an opportunity
to introduce students to various Earth
events and processes that will be studied
later in the year.
Visual
3 ASSESS
Evaluate
Understanding
L2
Ask students to write a five-question
quiz on this section along with an
answer key. Then have students ask one
another the questions.
Reteach
L1
Figure 21 Air pollution in the
Chinese city of Guangzhou. Air
quality problems affect many cities.
Interpreting Photographs
What may have contributed
to this air pollution problem?
threats to the environment include air pollution, acid rain, ozone
depletion, and global warming. The loss of fertile soils to erosion, the
disposal of toxic wastes, and the contamination and depletion of water
resources are also of considerable concern. The list continues to grow.
People must cope with the many natural hazards that exist such as
the one shown in Figure 22. Earthquakes, landslides, floods, hurricanes,
and drought are some of the many risks. Of course, environmental hazards are simply natural processes. They become hazards only when
people try to live where these processes occur.
It is clear that as world population continues to grow, pressures on the
environment will increase as well. Therefore, an understanding of Earth
is essential for the location and recovery of basic resources. It is also essential for dealing with the human impact
on the environment and minimizing the
effects of natural hazards. Knowledge
about Earth and how it works is necessary to our survival and well being. Earth
is the only suitable habitat we have, and
its resources are limited.
Figure 22 The damage here was
caused by a landslide that was
triggered by an earthquake.
Section 1.4 Assessment
Reviewing Concepts
1.
2.
Why do scientists study Earth as a system?
If a system is a collection of interacting
parts, what happens when one of the parts is
changed?
3.
What are the two sources of energy that
power Earth’s systems?
4.
List three ways that humans affect Earth’s
systems.
5.
Large numbers of tiny ocean organisms
die every day, fall to the ocean floor, are
buried, and are eventually converted to oil
and natural gas. Why are these two fuels
considered nonrenewable?
Section 1.4 Assessment
Answer to . . .
Figure 21 Sample answer: home
heating, motor vehicles, industry,
power plants
22
Chapter 1
6. Applying Concepts Describe the parts of a
tree in terms of it being a system.
7. Evaluating Is it possible for humans to have
no effect on any of Earth’s systems? Explain.
8. Applying Concepts How can scientists help
to prevent a natural process from becoming
an environmental hazard?
City Planning In Section 1.3, you learned
about Landsat satellite imaging. How can
data from Landsat help city planners determine where and where not to build?
22 Chapter 1
Use the outlines students created for this
chapter’s reading strategy to review the
main ideas from this section.
Images can show scars of landslides,
suggesting that the area may not be
stable.
Critical Thinking
1. Earth is a system made up of numerous
interacting parts, or subsystems.
2. Other parts may also change.
3. The sources are the sun and reactions in
Earth’s interior.
4. Sample answer: contaminating water,
polluting air, disposing of toxic waste
5. It takes too long (millions of years) for the
organisms to be converted into oil.
6. Roots transport food and water up through
the trunk, which holds the tree upright. The
trunk transports food and serves as support
for branches and leaves. Leaves help keep the
tree moist and shaded and release excess
water through pores.
7. No, every day you affect at least one of
Earth’s systems, even on the smallest scale.
Simply breathing changes the atmosphere
around you or stepping on the grass may
affect the biosphere beneath your foot.
8. Sample answer: They can analyze an area
to see if it is safe to live there. If the land is
unstable or subject to flooding, they may
make recommendations that people not
choose to live there.